MySQL move where clause inside subquery - mysql

Question

I have written the following MySQL query. However, I need to move the FIND_IN_SET where clause inside the sub query which joins the actions table.
Is this possible? When I try and move that part inside the subquery it gives me the error, paths column does not exist.
select
users_roles.role_id,
ar.actions,
a.paths
from users_roles
join
(
select
action_id,
role_id,
group_concat(action_id SEPARATOR ',') as actions
from actions_roles
) as ar on ar.role_id = users_roles.role_id
join
(
select
id,
group_concat(path SEPARATOR ',') as paths
from actions
) as a on a.id = ar.action_id
where
users_roles.user_id = 1 and FIND_IN_SET('/admin', paths);

Answer 1

It is possible, try this:
select
users_roles.role_id,
ar.actions,
a.paths
from users_roles
join
(
select
action_id,
role_id,
group_concat(action_id SEPARATOR ',') as actions
from actions_roles
) as ar on ar.role_id = users_roles.role_id
join
(
select
id,
group_concat(path SEPARATOR ',') as paths
from actions
having FIND_IN_SET('/admin', group_concat(path SEPARATOR ',')) > 0
) as a on a.id = ar.action_id
where
users_roles.user_id = 1
Since the paths column you are passing to the function is actually the result of group_concat() function inside your sub-query, all you need to do is add a HAVING clause in the sub-query and change the alias of the column with the actual call of the function, which you also use to generate the data.
Why HAVING and not WHERE?
Because you're verifying the result of group_concat() which is an aggregate function. And the result of aggregate functions can be filtered only through a HAVING clause.